1. Field of the Invention
The present invention relates to an electromagnetic stylus, and more specifically, to an electromagnetic stylus having an energy transforming device capable of converting variations in a physical quantity into electrical signals.
2. Description of the Prior Art
A conventional electromagnetic stylus is to utilize an electromagnetic induction method for performing touch operations. Generally, the electromagnetic stylus is an electromagnetic signal transmitting terminal and an electromagnetic sensor in a touch panel is an electromagnetic signal receiving terminal. When the electromagnetic stylus approaches the touch panel, the touch panel can calculate a touch position of the electromagnetic stylus according to variation of magnetic flux sensed by the electromagnetic sensor. Technology of driving the electromagnetic stylus to generate electromagnetic signals may be divided into two types: a passive induction method and an active induction method.
The major advantage of the passive induction method is that there is no need to install a battery into the electromagnetic stylus. The passive induction method involves utilizing a resonance circuitry in the electromagnetic stylus to receive and store alternating electromagnetic energy emitted by an antenna of a digital panel, and then transmit corresponding electromagnetic signals back to the digital panel for positioning of the electromagnetic stylus. However, the energy transforming efficiency between the digital panel and the electromagnetic stylus is lower than 0.5%.
On the other hand, the active induction method involves installing a battery into the electromagnetic stylus to provide the electromagnetic stylus with sufficient electrical energy for emitting electromagnetic signals. Accordingly, the electromagnetic stylus can actively emit electromagnetic signals to an X/Y-axis antenna array on a digital panel for positioning. However, in the active induction method, the volume and weight of the electromagnetic stylus may be increased due to installation of the battery. Furthermore, the battery changing operation may also cause a user much inconvenience.